Safety system for high-tension transmission-lines.



No. 833,211. PATENTED OCT. 16, 1906'.

J. 11. HILLIARD, J3. SAFETY SYSTEM FOR HIGH TENSION TRANSMISSION LINES.

APPLIO H FILED APB..20.1904.

i Witnesses. Inventor.

/W JAG/4M John D. Hil liard,Jr.

M W, by

JTbty.

UNITED srarns PATENT OFFICE.

JOHN D. HILLIARD, JR, OF GIJENS FALLS, NEW YORK. ASSIGN OR TO GEN- ERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

Specification of LettersPatent.

Patented Oct. 16, 1906.

Application filed April 20, 1904- Serial No. 204,075.

To all whom it may concern.-

Be it known that I, JOHN D.'HILLIARD, Jr., a citizen of the United States, residing at Glens Falls, county of Warren, State of New York, have invented certain new and useful Improvements in Safety Systems for High- Tension Transmission-Lines, of which the following is a specification.

This invention relates to systems of transmission of high-tension electric currents; and the object of the invention is to enable lines carrying heavy currents to be safely opened with moderate sized and not expensive switches. With the greatl increased use of such systems has come a emand for higher voltages and greater output of current, so that the switches are frequently unable to stand the strain of opening under excessive overloads unless, they are quite large and costly.

My invention aims to relieve this difliculty and enable smaller and less expensive switches to be used. In order to accomplish this, I use a series transformer connected in the line, two such transformers being used for a two-phase or three-phase circuit. Both the primary and secondary of this transformer are shunted by fuses or other automatic circuit-breaking devices, and across the secondary terminals is connected a tripcoil to operate the automatic line-switch. The action of these parts will be described hereinafter.

In the accompanying drawings, Figure 1 is a diagram showing my invention applied to a three-phase alternating-current circuit. Fig. 2 shows a direct-current circuit, and Fig. 3 a single-phase alternating-current circuit similarly equipped.

Let 1 represent a three-phase generator supplying current to the conductors 2 '3 4, two of which are provided with automatic circuit-breakers 5 6, which are released b the energizing of the trip-coils 7 8. In eac 1 of two legs of the line is the primary 9 of a series transformer. The secondary winding 10 of each transformer is in series with one of the trip-coils of the switch. 4 In shunt to each primary winding is a fuse 11 of a wide-opening or arc-extinguishing type. ho secondary windings are each short circuited by a fuse 12.

Under normal conditions of service the drop across'each primary winding is small,

owing to the mutual induction of the primary and the short-circuited secondary. The current in the secondary does not affect the trip-coil, because said coil is shunted by the fuse 12 but when an excessive overload is applied to the line the increased cur- 6o rent through the fuse 11 causes it to blow.

.The entire current is thereby thrown upon the primary, and the secondary current consequently increases and blows the fuse 12. This causes the secondary current to energize the trip-coil, release the switch, and open the line; but the instant'the fuse 12 blows the secondary circuit is practically opened by reason of the great resistance and self-induc tion of the trip-coil, which is wound to give this effect. The reactance' of the primary winding 9 is therefore greatly increased, causing a large drop across the terminals of said coil, and this affords a sure protection for the line-switch against the liability of blowing up, 7 5

so that smaller and less expensive switchescan be used than would be safe otherwise.

In Fig. 2 a direct current generator 13 is shown carrying a non-inductive load 14 and an inductive load I 15. Two automatic cir- 8o cuit-breakers are shown in circuit with the generator, one of which has its overload-coil 16 shunted by a non-inductive resistance 17 and a fuse 18, arranged in multiple, the overload-coil 1 9 of the other circuit-breaker being 8 5 similarly shunted by an inductive resistance 20 in multiple with a fuse 21. In the case of an overload the fuses 18 and 21 will blow and the resistances serve not only to protect the circuit-breakers from an excessive potential, but to force suflicient current through the coils 16 and 19 to trip the circuit-breakers.

in Fig. 3 the circuits and a, .p aratus are the same as in 2, except that the generator 22 a single-phase alternator' In accordance with the patent statutes I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment-thereof;- but I desire to have it we understood that the apparatus shown is only illustrative and that. the invention can be carried out by other means.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. The combination with an electric circuit, of an impedance in said circuit, a fuse in shunt to said impedance, a circuit-breaker..a'

trip-coil therefor, and means for energizing said trip-coil to open said breaker when an overload causes said fuse to blow and the ex-- cuit, of an inductance therein, an automatic fusible cut-out normally shunting the same,

a switch in circuit, and a trip-coil energized through the agency of the inductance when the automatic cut-out acts.

4. The combination. with an electric circuit, of an inductance, a trip-circuit of high impedance operatively related thereto, a trip-coil in said trip-circuit, an automatic cut-out normally shunting the inductance, and a switch governed by the trip-coil and in series with the inductance. I

5. The combination with a high-tension line, of an automatic switch, a series transformerin said line adapted to operate said switch, means. whereby an overload will practically open-circuit the secondary of said transformer, and a fuse short-circuiting the transformer primary.

'6. The combination with ahigh-tension line, of an automatic'switch, a series transformer in said line adapted to operate said switch, and fuses short-circuiting the transformer-windings.

- 7. The combination with a high-tension line, of a series transformer therein, an auto.

matic line-switch having a tri -coil 1n circuit with the transformer secon ary, and fuses short-circuiting the'windingsof said trans former.

8. The combination with a high-tension line, of a series transformer therein, anautomatic line-switch provided with a trip-coil' having high self-induction and connected in circuit with the secondary of said transformer, a fuse in shunt to the primary of said transformer, and a fuse short-circuiting the secondary thereof.

. 9. The 'comblnation with an electric circoil therefor, a cut-out in parallel relation to said trip-coil, an impedance shunting'the cut-out, and means for energizing the trip coil when the cut-out operates.

cuit, of an automatic circuit-breaker, a trip- 

